University of Reading (2009)

Greenhouse cucumber production systems in Oman : A study on the effects of cultivation practices on crop diseases and crop yields

Kiyumi, Khalifa Salem Muhammad

Titre : Greenhouse cucumber production systems in Oman : A study on the effects of cultivation practices on crop diseases and crop yields

Auteur : Kiyumi, Khalifa Salem Muhammad

Université de soutenance : University of Reading

Grade : Doctor of Philosophy (Ph.D.) : 2009

Résumé The greenhouse sector in Oman has expanded significantly since 2001. With expansion have come problems associated with the production system. A comprehensive survey of current farmer practice in relation to production and protection activities was conducted in northern Oman in 2001-2004. Results showed an annual increase in greenhouse number of over 40% per year. A number of serious problems associated with greenhouse crop production were identified, in particular : (1) over reliance on a single crop (cucumber), (2) substantial losses due to pests and diseases, especially damping-off caused by Pythium aphanidermatum, (3) dependence on pesticides for pest and disease control, especially for damping-off disease, (4) excessive application of irrigation water d fertilizers. A database of locations of all farms with greenhouses in northern Oman was made using GPS information and analysed using GIS techniques. Factors were identified which cause clustering ofgreenhouses in certain locations, including proximity to markets and centres ofpopulation. Other factors such as high irrigation .’ water salinity levels were identified as disincentives to greenhouse expansion. Natural epidemics of damping-off varied greatly in their temporal and spatial dynamics. Temporal progress was most rapid in the wanner seasons. Spatial dynamics were affected by temperature and position within the greenhouse. Results showed limited variation in pathogenicity among P. aphanidermatum isolates. Disease severity was negatively related to . . plant age, but positively related to temperature up to 3SoC. In the latter case this is a reflection of P. aphanidermaturrt growth in vitro. Comparisons between current fanner irrigation and fertilizer inputs and reduced inputs under controlled condit ons showed that yield and profitability of cucumber production could be increased from current levels. An analysis ofÃ‚Â· . economic factors related to greenhouse crop production indicated that yield was closely related to total cost of production, but not to h vels of pesticide input, suggesting inefficiencies in pest and disease management practices